Slap Happy Gibbs
NCIS Special Agent Gibbs is known for being a hardcore, no-nonsense leader. He has no problem with giving the very attractive, yet extremely obnoxious agent Michael Weatherly, otherwise known as agent Anthony DiNozzo, a quick smack upside the head when he needed it.
It turns out, the well-known and (full of tough love) head smacks were not the funny creation of the show’s writers. The smacks started when Mark Harmon got frustrated with his co-star during filming and slapped him on the head jokingly (or so they say). It fit the characters perfectly and became a common gag throughout the series.